According to the prior art, data packet transmission methods implement mechanisms for dividing packets into data blocks at the transmitting end, then for reassembling the blocks into packets at the receiving end.
In the MAC (“Medium Access Control”) layer, the data to be transmitted or MSDUs (“MAC Service Data Units”) are encapsulated in PDUs (“Protocol Data Units”) with an MAC header. When MSDUs are transmitted, they may be fragmented, whereby one or more parts (or fragments) of an MSDU are transmitted in the same PDU, while the remaining parts are transmitted in one or more other PDUs. One PDU may also comprise fragments of different MSDUs.
A method of this type implemented by a microprocessor of a receiving station compatible with an IEEE802.16 standard is shown in FIG. 1 and starts with an initialization step 10. Then, during a step 11, one or more data packets corresponding to an MSDU associated with a set of blocks are received. Then, during a step 12, the station identifies the correctly received blocks. Then, during a step 13, the microprocessor attempts to assemble the blocks received as MSDUs. The step 13 begins with a step 130 involving initialization of a current block pointing at the first received block. Then, during a test 131, the microprocessor checks whether the current block is valid (using for example an error detection code). If not, the step 13 ends with an MSDU assembly failure status. If so, during a step 132, the microprocessor builds an MSDU by inserting the current block into it. Then, during a test 133, the microprocessor checks whether the current block is the final block of the MSDU. If so, the step 13 ends successfully, with an MSDU being assembled. If not, in a step 134, the current block points to the following received block and the test 131 is reiterated. Thus, the MSDU assembly process is relatively long, since the number of elementary operations is high (at least three times (corresponding to the steps 131 to 133) the number of blocks present in an MSDU, with each of these blocks being tested by the microprocessor). This technique therefore has the disadvantage of being poorly adapted to applications which require significant reactivity (for example audiovisual flow transmission applications).